title: Seasonal fluctuations in serum concentrations of vitamin D metabolites in normal subjects.
mesh_terms: D000293:Adolescent; D000328:Adult; D002117:Calcitriol / Q000097:blood*; D002648:Child; D006801:Humans; D012621:Seasons; D013472:Sunlight; D014466:Ultraviolet Rays
chemical_list: D002117:Calcitriol